There is provided an implantable actuator for stimulating a patient's hearing, comprising a support frame (70), a dielectric electroactive polymer membrane (74) fixed and tensioned on the support frame, with the polymer membrane being provided with a first electrode (76) on one side and a second electrode (78) on the other side, means (80, 82, 84) for supplying electric signals to the electrodes, wherein the polymer membrane is for vibrating the cochlear liquid according to the electric signals supplied to the electrodes by direct contact or by contact with the round window membrane (88).
